Background: Activating mutations in the valine-to-glutamic acid substitution at position 600 of the v-raf murine sarcoma viral oncogene homolog B1 (BRAF-1) gene are detected frequently in patients with papillary thyroid carcinoma (PTC). These mutations have been identified in approximately 29% to 69% of PTCs and in >80% of PTCs of the tall cell variant, whereas they have not been detected in benign lesions or in the majority of those (80%) with the follicular variant of PTC. The objective of the current study was to evaluate the role of liquid-based cytology (LBC) for the detection of BRAF mutations in the outcome of patients who have thyroid PTC measuring ≤ 1 cm and, hence, in guiding their clinical and surgical management.
Methods: From October 2010 through June 2011, 230 consecutive cases were diagnosed as positive for malignancy on fine-needle aspiration cytology processed by LBC. Of these, 73 PTCs ≤ 1 cm underwent BRAF mutational analysis. The aspirated material was processed using an LBC technique. After DNA extraction of the residual material, BRAF mutation analysis was performed using a direct sequencing method.
Results: Fifty of 73 patients (68.5%) underwent surgery, and 34 of those patients (68%) had tumors that expressed a BRAF mutation (31 PTCs, including 11 tall cell variants and 3 follicular-variant PTCs). A significant association between BRAF mutation and bilaterality of cancer was observed (odds ratio, 0.077; P = .0007). BRAF mutation was associated significantly with lymph node involvement (odds ratio, 19; P = .0007) but not with extracapsular infiltration (odds ratio, 0.298; P = .179).
Conclusions: The current results indicated that BRAF gene mutations can be identified successfully on LBC material and using other cytologic methods with high reproducibility, feasibility, and informative results. The presence of a BRAF mutation may preoperatively predict the behavior of microscopic PTC, suggesting a more aggressive surgical approach.
Copyright © 2012 American Cancer Society.